Are you in the beginning stages of creating a workflow and one of your data sets is very large? One way to speed up the time it takes for testing is to select the option to Cache and Run on this data set. Alteryx will store this data set into your computer's cache.
Right-click on your large data-set and select Cache and Run Workflow.
A bubble will appear around your data set indicating it is put into your cache.
To clear this, simply click on the tool again and select Continue in the Configuration pane.
The detail behind this process is located here and is written by Alex Ko.
Alteryx basically writes a temporary yxdb file behind the scenes containing your data. The next time you run the workflow, it pulls from this file instead of querying the original data set.